1. Field of the Invention
The present invention relates to a display device, and more particularly, to an organic EL(electroluminescence) display panel and fabrication method thereof.
2. Discussion of the Related Art
Generally, as a size of a display device increases greatly, a flat panel type display panel occupying a small space attracts an attention.
Specifically, many efforts are made to study of fabricating a flat display panel using organic electroluminescent materials.
Organic EL display panels are divided into a passive matrix type panel and an active matrix type panel in accordance with driving methods.
In the passive matrix type display panel, scan electrode lines and data lines are arranged in rows/columns and pixels are formed at intersections between the rows and columns, respectively.
FIG. 1 illustrates a layout of a passive matrix type organic EL display panel according to a related art.
Referring to FIG. 1, an organic EL display panel includes pixels formed at intersections between scan and data electrodes crossing with each other like a matrix form.
And, the organic EL display panel further includes scan and data drivers applying currents to the scan and data electrodes, respectively so as to make the pixels emit light, respectively wherein the pixels are formed at the intersections between the scan and data electrodes crossing with each other.
A process of fabricating the organic EL display panel includes the steps of preparing a transparent substrate, forming a transparent electrode as a first electrode(anode) on the transparent substrate, forming an organic layer on the first electrode, forming a second electrode(cathode) on the organic layer using a metal compound, and forming a protecting layer on the second electrode.
The transparent substrate is formed of a glass material. As the transparent substrate fails to have electro-conductivity, ITO(indium tin oxide) is coated on the transparent substrate so as to form the transparent electrode.
Yet, ITO having great resistance is used after an auxiliary metal electrode has been formed.
Subsequently, barrier ribs are formed thereon, and then an organic material is deposited on an entire surface of the organic EL display panel so as to form an organic layer.
A scan electrode is then formed using a metal, thereby completing the fabrication process of the organic EL display panel.
In the constitution of the passive matrix type organic EL display panel, the number of pixels increases as the panel has higher resolution. Hence, the number of the scan and data electrode lines required for the more pixels increases as well.
If the number of the respective electrode lines increases, a time for one pixel to emit light is reduced in inverse proportion to the increase of the number.
Since the luminescent time for unit time of each pixel is reduced in inverse proportion to the increase of the number of the respective electrodes, instant brightness should become higher in order to overcome such a problem.
There are two kinds of general methods for complementing such a problem, which are shown in FIG. 2 and FIG. 3.
FIG. 2 and FIG. 3 illustrate layouts of complemented passive matrix type organic EL display panels according to a related art.
Specifically, FIG. 2 illustrates a structure of an organic EL display panel of which first electrode strip(anode strip) is divided into halves.
Referring to FIG. 2, a single electrode strip is divided into two strips. Each of the two strips performs an independent scan driving.
Thus, the number of scan for each strip is reduced half so as to improve a light-emitting efficiency and a device life time.
Yet, in the structure of the organic EL display panel, a data electrode is divided into both parties so as to need data drivers, which apply currents to the data electrodes, to be installed at both of the strips, respectively. Hence, product cost increases.
FIG. 3 illustrates a layout of an organic EL display panel of which first electrode strip(anode strip) is divided in a row direction.
Referring to FIG. 3, a width of a first electrode strip is reduced to a half of a conventional width, and an interval between scan electrodes is increased twice wider than a conventional one. Hence, the number of scan is reduced to half.
Even if the number of scan is reduced to half, the organic EL display panel shown in FIG. 3 requires no additional data driver applying a current to the data electrode. Yet, such a structure divides the width of the first electrode line into halves instead of a length direction, whereby an opening ratio is considerably reduced.
In order to overcome such a disadvantage, the opening ratio can be increased by using an insulating layer once more for an auxiliary electrode in the structure of the organic EL display panel. Yet, this method needs an additional step of forming the insulating layer, thereby increasing a product cost of the organic EL display panel fabrication as well as reducing a fabrication efficiency.